只能对较小的 k 得出具体结果.本文给出了我们利用计算机得到 k=3情况下 D—G 图的全部强同态.
Abstract
Consider the de Bruijn-Good graph Dn~k whose vertices represent the different n- tuple of integer αi∈{0
1
2
……k-1}
i=1
2
……
n and there exists arcs from vertex a=(α1
α2
…
αn)to b=(β1
β2
……
βn)iff αj=βj-1
j=2
……
n. A homomorphism Dn~k→D-(n-1)k is strong iff every arc fo Dn-11 is the image of arcs of Dn~k
In a recent paper
we proved that a strong homomorphism Dn~1→ Dn-1k can be introduced by a strong homomorphism D2~k→D1~k by this result and using computer we obtained all 1536 3-1 strong homomorphism Dn~3→Dn-13.